I think the major mistake that Intel made with the Prescott architecture was increasing the pipeline to 31 stages. If it wasn't for the lengthened pipeline and its associated heat and power issues Netburst would probably be alive and kicking today.
Excluding the pipeline lengthening, the improvements made to Prescott were pretty impressive. The improvements in branch prediction and the scheduler helped improvement effiency within the processor. While the processing power was also improved with the addition of a shift/rotater to a double-pumped fast ALU. Similarly, the addition of a dedicated integer multiplier freed up the FPU for other tasks. What's more the L1 cache was doubled to 16kb with associativity increased to 8-way. The trace cache has also been improved and the L2 cache quadrupled to 2MB in the Prescott 2M. Hyperthreading was also improved.
Sadly, all these improvements were used to hide the lengthened pipeline in Prescott. Which, while it didn't do completely, was fairly effective against the 55% increase in the pipelline. If Intel had kept the pipeline of Prescott the same length as Northwood while implementing all of Prescott's other improvements Netburst would still be competitive. Intel should have just relied on the shift from 130nm to 90nm to bring increases in clock speeds. Granted the clock speed increases allowed by relying just on a process shrink wouldn't be as great as the lengthening of the pipeline, combined with the other improvements, a Northwood with Prescott improvements would have remained competitive with AMD.
It is curious why Intel doesn't implement SOI. Even without SOI though, what Netburst needs to save it is Intel's upcoming 45nm process. Supposedly Intel has solved leakage problems with the 45nm process allowing phenominal power and heat reductions.
The Inquirer seems very excited by the prospects of the new process:
"So, if you hear gushingly good things about 45nm coming from IDF, believe it. If you hear anyone pooh-poohing Intel and its process tech because of the debacle that was 90nm, just point and laugh. This one will be very very good."
Sadly, Netburst won't survive long enough to realize the benefits of the 45nm process. However, I can only imagine the gains in clock speed, power reduction and heat production on Intel's already efficient next-generation Conroe, Meron, and Woodcrest architecture.
The Inquirer saids:
"Think happy thoughts here people, from what several sources have told the INQ, the leakage problem is solved, and I mean solved, not lessened. This will be a massive gain for Intel, and unless AMD and IBM can match it, it will pretty much hand it the mobile space, not to mention anything else where power matters."
Very promising.
http://www.theinquirer.net/?article=25512